[Changed] Constraining google-cloud-pubsub to not use version 2.31.0

[alcaptar]

🎩 What?

When shutting down workers, we have identifies a huge number of error being spammed:

Observed terminating stream error Cancelled('Locally cancelled by application!')

As stated in the pubsub documentation :

StreamingPull streams always close with a non-OK status. Unlike an error status for unary RPCs, this status for StreamingPull is just an indication that the stream is disconnected. The requests are not failing. Therefore, while the StreamingPull API might have a surprising 100% error rate, this behavior is by design.

So, for now, we are not gonna able to update to this specific google-cloud-pubsub version to avoid the spammy errors

🤔 Why?

To avoid the spammy issues